Does not allow images or HTML formatting

I have a real problem with my blog whenever I want to put images or html formatting in my text. FOr instance, I go into the editor and upload an image into the text and hit save. It takes me to the homepage of the blog and no image is placed on the text article. This happens with bold , text links and otehr formatting. It is as if the save doesn't work properly. I've tried fresh installs to no success and its all starting to get on my nerves.

If someone has encountered this before than please give me any hints on how I can remedy this. Thanks all.